Humans are still evolving, says Darwin Day keynote speaker
February 24, 2016 12:00 AM
Sarah Tishkoff — University of Pennsylvania evolutionary geneticist is the keynote speaker for Duquesne University’s Darwin Day celebration
By David Templeton / Pittsburgh Post-Gazette
Warning: Humans are still evolving.
People might think only bacteria and viruses are evolving, or perhaps some animals, birds and fish, but certainly not humans. But we’re not finished beings, forcing adaptation to the idea that human evolution continues.
That will be a key message at 7 p.m. Thursday in the Power Center Ballroom on the Duquesne University campus, when Sarah Tishkoff presents her keynote address, “African Evolutionary Genomics: A Modern Look at Human Genetic Diversity,” for the university’s Darwin Day celebration that’s free to the public.
The University of Pennsylvania evolutionary geneticist focuses her research on patterns of genetic variation in modern-day populations of Africa, where humankind began about 200,000 years ago, she said.
Indigenous African tribes living remotely, beyond most influences of modernity, have allowed her team to focus on genetic adaptation especially regarding disease exposure.
The Maasai People in southern Kenya and northern Tanzania, for example, herd cows and survive predominantly on cow’s milk and blood. For that reason, they have developed a genetic adaptation for lactose tolerance that evolved independently from Europeans.
Other African tribes are less vulnerable to malaria because of a protective gene mutation, she said. But that involved a tradeoff, with the mutation also making them more vulnerable to sickle cell anemia. Another genetic mutation among other Africans protects them against sleeping sickness but makes them more vulnerable to kidney disease and failure, she said.
A genetic adaptation that provided Pygmies a stronger immune function also reduced production of a growth hormone that explains their small stature. That means stronger immunity rather than smaller size was the key survival benefit of the mutation.
“We get a better understanding about the reasons for common disease by understanding evolutionary patterns,” said Ms. Tishkoff, who holds a Ph.D. in genetics and has received numerous awards for her work. Her studies of genetic variation involve field and laboratory work along with computational analysis.
Understanding the genetic basis for various traits in indigenous populations led her team to trace African lineages to four distinct groups, based on specific language characteristics, and how each adapted and continues adapting differently for survival.
“Evolution still is occurring and people are still evolving,” she said. “We recently saw evolution in action with Ebola, with 50 percent surviving the infection. What gene variation allowed them to survive?”
Michael Seaman, a Duquesne University associate professor of biology, said it has long been known that modern humans originated in Africa, “but the amount and patterns of genetic diversity within that continent have been relatively understudied.”
“Dr. Sarah Tishkoff is one of the leading researchers in the world examining the genetic variation in Africa using modern methods including whole genome sequencing,” he said, noting her selection as Darwin Day speaker. “We are excited to bring her to Pittsburgh for this event.”
Darwin Day, organized by Mr. Seaman and Duquesne biologist David Lampe, is held each February to celebrate the life and work of Charles Darwin, who first described evolutionary principles with publication in 1859 of his book, “On the Origin of Species” and the “Descent of Man” in 1871. The celebration also stresses the importance of science education.
“While not everyone in Pittsburgh may be as excited by the evolution of fruit flies and worms and frogs as we scientists are, I think everyone has an inherent interest in our own origins — who we are and where we came from,” said Mr. Seaman, who holds a Ph.D. in biological anthropology. “So we really wanted to bring in an expert in human evolution this year.”
David Templeton: email@example.com or 412-263-1578.
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